It is important specifically in the medical field such as a clinical site to detect a cell infected with pathogenic bacteria and a cell in a predetermined form from a large number of cells. As a method for quickly, easily, and highly accurately detecting such a cell, a method below is introduced, for example. In this method, a plurality of micro chambers (wells) is formed on a microarray chip, and fluorescently-labeled cells are filled in the wells. The wells are then observed through a fluorescence microscope while applying a laser light beam, and a certain cell emitting fluorescence is detected.
Moreover, such a configuration is known in which a series of wells filled with cells is scanned with a laser light beam to detect fluorescence emitted from the cells. In this configuration, wells are concentrically formed as the wells are arranged in the radial direction of a disk, and a series of information pits is formed in a track shape on a layer isolated on the light beam incident side from a layer on which the wells are formed as the information pits are arranged along the arrangement of the well. The information pits are formed according to the formats of CDs and DVDs, and the information pits hold information such as address information.
In this configuration, in an optical system that detects fluorescence, a light source that applies a laser light beam to the wells and a light source that applies a laser light beam to the information pits are separately prepared, and the laser light beams emitted from the light sources are converged through a shared objective lens. The objective lens is controlled in such a manner that the laser light beam for information pits is focused on the information pits and caused to follow a series of information pit strings (a track). Thus, a series of the wells is in turn scanned with the laser light beam for wells, and the laser light beam for wells is focused on the cells filled in the wells. When fluorescence is emitted from the cells by applying the laser light beam, this fluorescence is detected by a fluorescence detection photodetector. The presence or absence of a detection target cell is automatically detected out of a large number of cells accommodated in a series of the wells arranged on the disk based on the output from the photodetector, without observation using a fluorescence microscope.